Mold Growing on Roots--Need Advise!

[amberella618]

Hi all

I was hoping for some advise on an emerging problem. One of my Paphs and an Oncidium have recently had a pretty significant amount of mold growing on their roots. It looks like your average bread mold-- white and fuzzy. It is growing on the base of the roots and even a little on the hydroton.
Does anyone know how to resolve mold problems? Here's a little info on my setup:
I grow using the "semi-hydro" method with hydroton as the media. For the nutrient solution I use Dyna-Gro Orchid-Pro 7-8-6 with several additives. I use RO water so I add a cal-mag formula, a silicate called Pro-Tekt and Liquid Karma which has Humic Acid, Soluble Potash, and available phosphate. The PPM is typically around 700 and the pH is stays around 6.1 (any info on optimal PPM, EC, and pH would also be greatly appreciated!). For lighting I run a 250W High Pressure Sodium dimmed anywhere between 150W-200W in the afternoon and maintain them on several LED lights. The humidity has been a bit of a wild card lately getting up very high (100%) but with a few exceptions it is kept around 75%. It never stays high (95-100%) for extended periods of time but I'm not sure if 75% is even too high. The temp is pretty constant during the day at about 82 and about 75 at night.
Only 2 of the 6 orchids in the greenhouse have mold on their roots.. Unfortunately the affected ones are both about to bloom for the first time so I would really like to keep them healthy.
Any info would be greatly appreciated!!

[silken]

I'm not much help with your growing conditions, but just to give you a bump.

[Bud]

Do you flush it twice a month? I have problems with algae but not with molds(molds are fungi) so you may want to spray fungicide...

[amberella618]

I appreciate the help. The "bump" is also helpful-- I'm new to the forum so any comment makes me feel a little better about posting...

I've reduced the humidity and increased airflow but the mold is growing I think it will have to come down to a fungicide.

Bud, what kind of conditions do you keep your orchids in (ie. PPM, pH, humidity, temp, ect)?

[Eyebabe]

I am also at a loss to suggest what might help.
Isopropyl Alcohol will kill the mold AND your roots.
Other than that, I would consider removing the affected media (repotting if necessary) and the affected root.
Are you sure it's mold??

[greenpassion]

I have been reading these posts about mold growing on hydroton, and I too have an issue with mold. I currently am using a bark mix with moss-but plan to switch to S/H culture as soon as I can drill some holes into my glass bowls. ( I know I could use pots already made for S/H but I love the way glass looks!) Anyway, my question is does this white fuzzy mold hurt the orchid? I have used Garden Safe fungicide just recently and the jury's out as to wether or not it works.....

[Olivia]

I'm fairly new to the s/h myself but when I noticed early on some of the same mold. It turns out it was when some of the old roots were rotting. So I unpotted trimmed up those roots (there were about a million new ones at this point so it was ok) cleaned the hydroton and flushed with physan for good measure.

And I haven't seen any mold since and it's been about four months.

[RJSquirrel]

I think olivia got it right how to limit the mold growth


Mold is spread thru the air, by water, or by insects and can land anywhere and grow. The environment is just too good for them to pass up in a wet plant if you have spores flying around the home. They live on any dead material as they are recyclers. Left alone it will cause problems with your orchids. So my thoughts are mold can hurt your orchids if left unchecked and untreated.

[Rivka]

It seems to me that you have your nutrients up too high, not sure if that is related at all but it is something you also asked about. Yours is 3 or 4 times what I use. I have hear a lot of numbers but most in the 75-150 range for most waterings. Most folks aim for a clear water flush every so often with that as well.

Your humidity and temp is impressively high, it would depend on your orchids whether that is too high or not. I know with my intermediate growers it would be, specially the low only being 75 degrees. And with humidity that high I hope your airflow is super high!

You mention just 6 orchids in your greenhouse, are the conditions set that extreme for other plants your growing? I wish I could get higher humidity in my growing area, but for my collection I would aim for 60-70% could see higher causing issues and not really having benefits. Now if I had a cool greenhouse and was simulating a cloud forest....